Mongoose field match populate - node.js

Question

I'm having some trouble with how best to implement this join/query in mongoose.
var mongoose = require('mongoose');
var addressSchema = new mongoose.Schema{
rank: Number,
address: String,
tag_name: String,
tag_url: String};
var tagSchema = new mongoose.Schema{
address: String,
name: String,
url: String};
I have a bunch of addresses saved and a bunch of tags saved. Some addresses have tags, most do not. I update the addresses and tags separately frequently. What I want to do is query some specific addresses and return them as an array with the tag fields filled in (the address tag fields are blank in the database).
So for example, I want to do this without making a db query for every address(101 db queries in the example). I'm not sure if $match or $in or populate is what I'm looking for. The below code is untested and may not work, but it should give you an idea of what I'm trying to do.
var db = require('../config/dbschema');
// find an array of addresses
db.addressModel.find({ rank: { $lte: 100 } }, function(err, addresses) {
// now fill in the tag fields and print
addTagField(0, addresses);
});
// recursive function to fill in tag fields
// address tag name and tag url fields are blank in the database
function addTagField(n, addresses) {
if(n < addresses.length) {
db.tagModel.find( { address: addresses[n].address }, function(err, tag) {
// if find a tag with this address, fill in the fields
// otherwise leave blank and check next address in array
if(tag) {
addresses[n].tag_name = tag.name;
addresses[n].tag_url = tag.url;
}
addTagField(n+1, addresses);
});
} else {
console.log(addresses);
}
}
http://mongoosejs.com/docs/api.html#aggregate_Aggregate-match
http://mongoosejs.com/docs/api.html#query_Query-in
http://mongoosejs.com/docs/api.html#document_Document-populate
I want to do what the above does with fewer db queries.

Answer 1

Your major problem is that you're not taking advantage of Mongoose's relationship mapping. Change your schemas just a bit and your problem will easily be solved. You can do it like this:
var tagSchema = new Schema({
name: String,
url: String,
})
var addressSchema = new Schema ({
rank: Number,
address: String,
tags: [tagSchema],
})
addressModel.find({rank: {$lte: 100}}, function(err, addresses) {
...
})
or this:
var tagSchema = new Schema({
name: String,
url: String,
})
var addressSchema = new Schema ({
rank: Number,
address: String,
tags: [{type: ObjectId, ref: 'Tag'}],
})
addressModel
.find({rank: {$lte: 100}})
.populate('tags', 'name url')
.exec(function(err, addresses) {
...
})

Answer 2

I didn't want to embed the docs. The is what I came up with.
db.addressModel.find({ rank: { $lte: 100 } }, function(err, addresses) {
if(err) return res.send(400);
if(!addresses) return res.send(404);
var addrOnlyAry = addresses.map(function(val, idx) { return val.address; });
db.tagModel.find( { address: { $in: addrOnlyAry } }, {}, function(err, tags) {
if(err) return res.send(400);
if(tags.length > 0) addresses = setTagFields(addresses, tags);
return res.json(addresses);
}
}
function setTagFields(addresses, tags) {
for(var i=0; i < tags.length; i++) {
for(var j=0; j < addresses.length; j++) {
if(addresses[j].address === tags[i].address) {
addresses[j].tag_name = tags[i].tag;
addresses[j].tag_url = tags[i].url;
break;
}
}
}
return addresses;
}